Keywords:

Abstract:

This report summarizes the results of a test program
conducted in 2006 and 2007 by the North American Fire
Testing Laboratories (NAFTL) consortium.
Gypsum/steel-stud wall assemblies, nominally rated at
1-h, were tested by six different organizations in North
America employing ten different furnace facilities
following the guidance provided in ASTM E 119-00. The
participating NAFTL laboratories arrived at an identical
1-h rating for the gypsum wall specimen tested according
to their respective standard operating protocols. The
average time to failure (defined by the temperatures
reached on the unexposed side of the specimen) was 65 -
2.8 minutes. The variability in individual peak
thermocouple temperatures measured at similar locations
on the different wall assemblies exceeded - 50DGF around
one hour into the test, and reached a maximum of close
to - 150DGF at the average time of failure. Differences
in the time to failure for the ten close-to-identical
wall assembly tests did not correlate at a statistically
significant level with differences in average furnace
temperature, the temperature-time integral, changes in
ambient temperatures, or standard deviation among the
furnace control thermocouple temperatures. Six
inter-laboratory tests were also conducted by several
Japanese organizations, yielding an average time to
failure of 67.1 - 1.1 minutes. The inter-laboratory
program described in this report is the largest ever
conducted for fire resistance testing and forms the
basis for future programs aimed at testing addential
structural materials, elements and systems subjected to
fire test standards referenced in building codes.

The National Institute of Standards and Technology (NIST) is an agency of the U.S. Commerce Department.